i found this list of feats somewhere on the forum, and thought it was interesting. not sure it will convince anyone that supes really IS stronger, but they are impressive nonetheless:
<<Credit to RedWolf:
JLA: World War Three story-line: Superman was chained to the endless millwheels of the Mageddon machinery. His strength was used to move the gears of a weapon whose size dwarfed the entire Earth/Moon system. Once again it dwarfed the entire Earth/Moon System.
In Superman: The Earth Stealers, Superman propelled a massive space station, cylindrical in shape and stated to be 600 miles in diameter (the length of the cylinder, judging by the depiction, had to have been about 2500 miles ) by pushing against it. The weight was inestimable- it was constructed from all the natural resources gleaned from an entire solar system. A hyperspace portal was opened and Superman not only pushed it, he propelled it for 20 minutes through hyperspace (it was stated that they reached the halfway point at 10 minutes). He had to exert the power to move it at the same time that he had to deal with the stresses of hyperspace unprotected.
JLA #77: Superman contains a black hole in the palm of his hand for an undisclosed amount of time. Later, he produces static electricity sufficient to be "corralled" by Green Lantern John Stewart into containing the black hole. Superman then launches the black hole into a neighboring wormhole.
Luthor 2000 special: Superman split one of Saturn's moons with a single strike.>>
others have mentioned some astounding feats as well.